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Addendum

Five micrograms per deciliter (5 µg/dL) was adopted by CDC in 2012 as the upper reference range value for BLLs in children as an advisory level for environmental and educational intervention [ACCLPP 2012].

In 2015, NIOSH designated 5 µg/dL of whole blood, in a venous blood sample, as the reference blood lead level for adults. An elevated BLL is defined as a BLL ≥5 µg/dL. This case definition is used by the CDC's Adult Blood Lead Epidemiology and Surveillance program (ABLES tracks elevated BLLs among adults in the United States), the Council of State and Territorial Epidemiologists (CSTE), and CDC's National Notifiable Diseases Surveillance System (NNDSS). Previously (i.e. from 2009 until November 2015), the case definition for an elevated BLL was a BLL ≥ 10 µg/dL. The U.S. Department of Health and Human Services recommends that BLLs among all adults be reduced to <10 µg/dL.

In contrast to the CDC reference level, prevailing Occupational Safety and Health Administration (OSHA) lead standards allow workers removed from lead exposure to return to lead work when their BLL falls below 40 µg/dL. However, NIOSH "(the research arm of OSHA)" recommends that the most current guidelines for management of lead exposed adults be implemented by the medical community at the current CDC/NIOSH reference BLL of 5 µg/dL. http://www.cdc.gov/niosh/topics/ables/description.html

Learning Objectives

Upon completion of this section, you will be able to

identify the CDC's level of concern for lead in children's blood

identify the OSHA blood lead level for first intervention from occupational exposure to lead

describe the types of environmental standards in the U.S.

Introduction

Because of lead's importance as a cause of public health problems, a number of federal agencies have issued advisory standards or enforceable regulations that set lead levels in different media. The table below summarizes these standards and regulations for 2006; see subsequent sections for further explanation.

Biologic Guidelines

As new information has emerged about the neurological, reproductive, and possible hypertensive toxicity of lead, and as parameters that are more sensitive are developed, the BLLs of concern for lead exposure have been progressively lowered by CDC. (See Figure 1 below).

Figure 1. Lowering of CDC-recommended action level for blood lead in children over time.

Ten µg/dL (micrograms /deciliter) was adopted by CDC in 1991 as an action level for children, an advisory level for environmental and educational intervention.

Physician Reporting Requirements

Most states ask or require primary care physicians and persons in charge of screening programs to report both presumptive and confirmed cases of lead toxicity to the appropriate health agency. This is to ensure

abatement of the lead source

education of the patient

remediation steps are undertaken

In some states, the clinical laboratories performing blood lead testing are required to report cases of lead toxicity.

Even if not required, a physician should strongly consider consulting a health agency in the case of lead toxicity, as health agencies are important sources of resources and information.

In some states, laboratories performing BLL or EP (ZPP) tests are also required to report abnormal results to the appropriate health agency.

Workplace Air

The
OSHA Lead Standard
specifies the permissible exposure limit (PEL) of lead in the workplace, the frequency and extent of medical monitoring, and other responsibilities of the employer.

OSHA has set a PEL (enforceable) of lead in workplace air at 50 µg/m3 averaged over an 8-hour workday for workers in general industry.

For those exposed to air concentrations at or above the action level of 30 µg/m3 for more than 30 days per year, OSHA mandates periodic determination of BLLs.

If a BLL is found to be greater than 40 µg/dL, the worker must be notified in writing and provided with a medical examination.

If a worker's one-time BLL reaches 60 µg/dL (or averages 50 µg/dL or more on three or more tests), the employer is obligated to remove the employee from excessive exposure, with maintenance of seniority and pay, until the employee's BLL falls below 40 µg/dL.

The ACGIH has set a threshold limit value for a time-weighted average (TLV/TWA) of 50 µg/m3 for lead in workplace air (except for lead arsenate).
http://www.acgih.org/home.htm.

Soil

Lead contaminated soil can pose a risk through direct ingestion, uptake in vegetable gardens, or tracking into homes.

Uncontaminated soil contains lead concentrations less than 50 ppm but soil lead levels in many urban areas exceed 200 ppm. (AAP 1993)

The EPA's standard for lead in bare soil in play areas is 400 ppm by weight and 1200 ppm for non-play areas. This regulation applies to cleanup projects using federal funds.

The soil screening level [PDF - 1.43 MB]
(SSL) for lead represents a conservative estimate for a level that would be protective of public health in residential soils based on an analysis of the direct ingestion pathway for children. This value is for guidance only and is not enforceable.

Drinking Water

EPA has set drinking water standards with two levels of protection.

The maximum contaminant level goal (MCLG) is zero. This is the levels determined to be safe by toxicological and biomedical considerations, independent of feasibility.

The use of lead solder and other lead-containing materials in connecting household plumbing to public water supplies was banned by EPA as of June 1988.

Many older structures, however, still have lead pipe or lead-soldered plumbing internally, which may substantially increase the lead content of water at the tap.

Regulations controlling the lead content of drinking-water coolers in schools went into effect in 1989.

Residents can buy inexpensive drinking water lead screening kits
(see http://www.afhh.org/ or hire professionals to test their water.

Food

FDA has set a number of action levels (enforceable) and levels of concern for lead in various food items. These levels are based on FDA calculations of the amount of lead a person can consume without ill affect.

For example, FDA has set an action level of 0.5 µg/mL for lead in products intended for use by infants and children and has banned the use of lead-soldered food cans. (FDA 1994 and FDA 1995 as cited in ATSDR 1999)

Paint

White house paint contained up to 50% lead before 1955. Federal law lowered the amount of lead allowable in paint to 1% in 1971. The CPSC has limited since 1977 the lead in most paints to 0.06% (600 ppm by dry weight). Paint for bridges and marine use may contain greater amounts of lead.

Table 3: Standards and Regulations for Lead

Agency

Media

Level

Comments

CDC

Blood

10 µg/dL

Advisory; level for individual management

OSHA

Blood

40 µg/dL
60 µg/dL

Regulation; cause for written notification and medical exam
Regulation; cause for medical removal from exposure

ACGIH

Blood

30 µg/dL

Advisory; indicates exposure at the threshold limit value (TLV)

OSHA

Air (workplace)

50 µg/m3
30 µg/m3

Regulation; PEL (8-hr average.) (general industry)
Action level

CDC/NIOSH

Air (workplace)

100 µg/m3

REL (non-enforceable)

ACGIH

Air (workplace)

150 µg/m3
50 µg/m3

TLV/TWA guideline for lead arsenate
TLV/TWA guideline for other forms of lead

Regulation; by dry weight. There is a new standard for lead in children's jewelry.

Key Points

CDC lowered the recommended blood lead action level for lead exposure in children to10 µg/dL in 1991.

States may have their own levels of concern for adults and children.

Most states have reporting systems for lead poisoning.

OSHA has set required standards for the amount of lead allowed in workroom air at 50 µg/m3 averaged over an 8-hour workday.

EPA has set a standard for lead in the ambient air of 0.15 µg/m3 averaged over a calendar quarter.

EPA has established 400 ppm for lead in bare soils in play areas and 1200 ppm for non-play areas for federally funded projects. This may be used as a guidance level elsewhere.

EPA's action level for lead in water delivered to users of public drinking water systems is 15 µg/L. Its goal for lead is zero.

FDA has set various action levels regarding lead in food items. Use of lead-soldered food cans is now banned.

Today, paint intended for residential use is limited to 0.06% lead content.

Progress
Check

5. The CDC's action level of 10 µg/dL for children's blood is

A. the blood lead level below which no effects have been found
B. also used by OSHA as a level of concern in workers
C. an advisory level for environmental and educational intervention
D. a regulatory level at which children must be removed immediately removed from any pre-1978 residences